With reference to FIG. 11, description will be given of how a radio base station eNB in a mobile communication system of the LTE (Long Term Evolution) system operates to transmit a paging signal for notification of an incoming call for a mobile station UE belonging to any one of multiple groups #1 to #3 (that is, a paging signal transmission method).
As shown in FIG. 11, the radio base station eNB is configured to transmit a PDCCH (Physical Downlink Control Channel) including a P-RNTI (Paging-Radio Network Temporary Identifier), in a subframe for the group #1 (in the example in FIG. 11, a subframe #0 in a radio frame #0), upon detection of an incoming call for the mobile station UE belonging to the group #1.
Note that, the radio base station eNB is configured to use the PDCCH to notify, to the mobile station UE belonging to the group #1, the resource block position, the resource block size, and the like of a PDSCH (Physical Downlink Shared Channel) to which a PCH (Paging Channel) for the group #1 (i.e., a paging signal for notification of an incoming call for a mobile station UE belonging to the group #1) is mapped.
Moreover, the radio base station eNB is configured to use the PDSCH to make notification of identification information (UE-ID) on the mobile station UE which is to receive the above-described incoming call.
Meanwhile, the mobile station UE is configured to monitor whether or not the PDCCH including the P-RNTI is transmitted, at discontinuous reception intervals (paging DRX intervals) for the group #1.
The mobile station UE is configured to receive the PDSCH corresponding to the PDCCH, on the basis of information included in the PDCCH (e.g., the resource block position, the resource block size, and the like of the PDSCH), when judging that the PDCCH including the P-RNTI has been transmitted.
The mobile station UE is also configured to perform incoming call processing with the radio base station eNB, when the UE-ID included in the received PDSCH is a UE-ID addressed to itself.
Non-patent Literature 1: 3GPP TS36.300, “E-UTRA and E-UTRAN; Overall description; Stage 2”, v8.1.0.
Non-patent Literature 2: R2-073372, “Paging Procedure in LTE”, NTT DoCoMo, Inc., NEC.
However, with a conventional paging signal transmission method implementable in the mobile communication system of the LTE system, only one subframe (1 ms) is allowed to be set in each radio frame (10 ms) and used to transmit the PCH (paging signal) for each group.
Thus, such mobile communication system has a problem that the PCH may not possibly be mapped to the subframe in a case where the cell bandwidth is narrow, another signal (e.g., BCCH: Broadcast Control Channel or the like) is mapped to the subframe, or some other cases.